The invention relates to a magnetic-tape cassette comprising a housing having two rectangular major walls, two long side walls and two short side walls, in which major walls two reel hubs are mounted for rotation, a first one of said long side walls being formed with apertures past which a length of magnetic tape which is unwound from and taken up by the reel hubs is guided by means of a pair of tape guides which are arranged at or near corners of the cassette housing and around which the magnetic tape passes in contact therewith.
A magnetic-tape cassette of this type, described in U.S. Pat. No. 3,394,899, is known by the name of "Compact Cassette". Generally, a comparatively large length of the magnetic tape is accommodated in the comparatively small cassette housing. Due particularly to inaccuracies in the attachment of the end of the magnetic tape to the reel hub, problems may arise when the magnetic tape is wound onto the relevant hub in that the turns of the tape are axially shifted while being wound, giving rise to so-called "telescoping". This telescoping of the magnetic tape generally gives rise to jamming of the tape inside the cassette housing as a result of friction against the major wall. Telescoping of the magnetic tape is an effect which has been known for many years and has lead to the development of various means for precluding such axial displacement of the turns of tape during winding. U.S. Pat. No. 3,675,875 describes an example of such means comprising corrugated polyester foil arranged between the turns of tape and the major walls. In principle these known corrugated foils, in the same way as other known anti-telescoping means, do not effectively eliminate the cause of telescoping, namely an incorrect attachment of the tape to the reel hubs. Therefore, despite all these solutions telescoping still occurs in practice, the known means merely serving to minimize this telescoping effect. Often the attendant friction between the respective tape edge and the foil, which are in contact over a comparatively large distance, still impairs the tape transport.